The program envisioned under this program project grant will comprise a coordinated research effort on The Biologic Effects of Environmental Radiation, particularly of ultraviolet and visible light, with emphasis on effects on the skin. The separate projects will be supervised by individual investigators of senior scientific stature (see below). As can be seen, the main interests of the investigators conform with the scope of the program to the end that the separate groups will cooperate closely under the coordinating leadership of the principal investigator. The main projects to be carried out and the senior investigators in charge are: Core Services: D. Berger, MSEE; M. Logani, Ph.D.; S.J. Mann, Ph.D.; R.E. Davies, Ph.D. Optical Physics and Instrumentation: D. Berger, MSEE. Photochemistry: R. E. Davies, Ph.D. Comparative Photobiology: Associate Professor to be named. Phototherapy: F. Urbach, M.D. and T. R. C. Sisson, M.D. Environmental Photobiology: P. D. Forbes, Ph.D. Collaborative Research: P. D. Forbes, Ph.D. and D. Berger, MSEE.